First, there existed a Celtic language known as Gaulish, which was spoken by the Gauls before the arrival of the Romans. The Gauls were the Celtic ancestors in France and are today still popular as a symbol of the French national identity. This is particularly expressed in the comics of Asterix, in France better known as Astérix le Gaulois, which is directly referring to the Gaulish background.
Although the Gauls were represented as very brave people in the Asterix comics, they were actually, like many other nations, conquered by the Romans. The Romans quickly introduced the Latin language, as they did in all their conquered areas. This brought extreme linguistic changes to the region of Gaul, what we today know as France.
Later on, in the 3rd century the Franks arrived. The Franks were a Germanic tribe and had a strong impact on what would later become Modern French. Furthermore, the arrival of tribes like the Burgundians, Visigoths and Alemanni led to drastically changes within the vowel system and syntax of the language.
During the 13th century the unification of the Normandy and the Kingdom of France took place, which also had a huge influence on the history of the French language. As a result, there were added many Scandinavian words to Old French via the Norman language.
The Kingdom of France later declared Middle French as the official language, banishing Latin and other regional languages like Occitan and the Oil languages. By the 17th century, the rise of French literature put forward French bureaucracy. This, in turn, led to what is known now as Classical French, what later evolved into Modern French. Finally, Modern French became a lasting legacy of the French colonialism.